Document matching on CCITT Group 4 compressed images

A method is proposed for detecting whether two CCITT group 4 images were scanned from the same document. Features are extracted from rectangular patches of text and compared with a modified Hausdorff distance measure. Two images are said to be ‘‘equivalent’’ (i.e., they were scanned from the same document) if the Hausdorff measure finds that a specified number of features are located within a given distance of one another in both images. This paper explains the technique and presents experimental results that demonstrate its effectiveness. It is shown that features extracted from a one-inch square patch of image data provide better than 95% correct retrieval accuracy with no false positives on a database of 800 documents.